However, in order to have credibility, the claim should be supported by some proof, and a descriptive element. Of course, this is often difficult as no one knows you numbers other than yourself (unless you are a public company, where it must be shown).

Some examples:
- Number 1 in website traffic as shown by Alexa.
- Number 1 in total leads generated, as shown by x leads versus Company A, B, and C, which have y leads.
- Number 1 in Design, as shown by The Webbies
….etc…etc…

In the example above, it seems that the website would be:
- Number 1 in terms of frequency of updating listings

Of course, this should be proven with examples as the time it takes other companies to update their listings. As well, it should show the number of listings on each website, as a website with 1,000 listings is easier to update than a website with 1,000,000 listings. It should also show what aspects of the listing are being updated, as some aspects might be much easier to update than others.

I always like to think of a Number 1 website as the one with the most website traffic, but as mentioned above, that is hard to measure as Alexa is not always so accurate, especially with websites with of 80,0000+.

Matthew – #1 coolest guy, ever.

Clearly you are confident in the superiority of your product; even if your claims are accurate, wouldn’t they still be #1? Most people/companies I know use traffic metrics to determine who is #1. Eg. I prefer Bing over Google, but clearly realize that Google is #1

I have no favorites in this discussion, but see a lot of sites claim to be #1 of this or that, but in most cases, the guys who are, in fact #1 are not those making the claims. Online, typically #1 refers to that site which is the busiest, no?